diff --git a/src/FPPrac/Prelude.hs b/src/FPPrac/Prelude.hs
--- a/src/FPPrac/Prelude.hs
+++ b/src/FPPrac/Prelude.hs
@@ -18,20 +18,27 @@
 
 import Prelude hiding (length,(!!),replicate,take,drop,splitAt)
 import qualified Prelude as P
-import Data.Char (ord,chr)
+import qualified Data.Char (ord,chr)
 
 import FPPrac.Prelude.Number
 
 default (Number)
 infixl 9 !!
 
+ord :: Char -> Number
+ord = I . toInteger . Data.Char.ord
+
+chr :: Number -> Char
+chr (I i) = Data.Char.chr (fromInteger i)
+chr n     = error $ "ord undefined for float: " ++ show n
+
 -- | /O(n)/. 'length' returns the length of a finite list as a 'Number'.
 length :: [a] -> Number
 length = I . toInteger . P.length
 
 -- | List index (subscript) operator, starting from 0.
 (!!) :: [a] -> Number -> a
-xs !! (I i) = xs P.!! (fromInteger i)
+xs !! (I i) = xs P.!! fromInteger i
 _  !! _     = error "trying to index (!!) using a floating number"
 
 -- | 'replicate' @n x@ is a list of length @n@ with @x@ the value of
diff --git a/twentefp.cabal b/twentefp.cabal
--- a/twentefp.cabal
+++ b/twentefp.cabal
@@ -1,5 +1,5 @@
 Name:                twentefp
-Version:             0.4.1
+Version:             0.4.2
 Synopsis:            Lab Assignments Environment at Univeriteit Twente
 Description:         Lab Assignments Environment at Univeriteit Twente
 License:             BSD3